1. Field of the Invention
The present invention relates to a die for forming a honeycomb structure, and a method of manufacturing the die, and particularly relates to a die for forming a honeycomb structure, and a method of manufacturing the die in which wear resistance is superior and in which pressure resistance can be reduced to realize sophisticated formability.
2. Description of the Related Art
As a method of manufacturing a honeycomb structure of a ceramic, an extruding method has been heretofore broadly performed using a die (hereinafter referred to simply as the die in some case) for forming a honeycomb structure. The die comprises a die substrate having: a back hole for introducing clay (green material); and a clay extruding slit which communicates with the back hole and which is formed into a lattice form or the like. In this die, usually the back hole for introducing the clay is disposed in an opening having a large area in one surface (surface on a clay introduction side) of the die substrate. The clay extruding slit is disposed into the lattice form or the like having a small width corresponding to a partition wall thickness of the honeycomb structure in the surface on a formed article extrusion side opposite to the clay introduction side of the die substrate. Moreover, each back hole is usually disposed in a position where the latticed clay extruding slits intersect with each other, and the back hole communicates with the slit inside the die substrate. Therefore, the clay formed of a ceramic material or the like introduced from the back hole moves from a clay introducing hole having a comparatively large inner diameter into the clay extruding slit having a small slit width, and is extruded from the clay extruding slit to constitute a formed article having the honeycomb structure.
As this type of die for forming the honeycomb structure, for example, there has been disclosed a die for forming the honeycomb structure, in which a diamond film or a diamond-like carbon film is formed on the surface of the die substrate in order to enhance wear resistance (see Japanese Patent Application Laid-Open No. 2002-339068). There has been disclosed another die for forming the honeycomb structure, in which an underlayer, and a surface layer are formed in this order on the film substrate, and the surface layer is constituted of tungsten carbide particles containing a main component of W3C and having an average radius of 5 μm or less (see International Publication No. 03/039828).
However, in the die for forming the honeycomb structure, described in Japanese Patent Application Laid-Open No. 2002-339068, there has been a problem that the layer (underlayer), constituting the substrate of the diamond film or the diamond-like carbon film, has low smoothness, this underlayer has a large influence on the smoothness of the diamond film or the diamond-like carbon film formed on this underlayer, this lowers the smoothness of the surface of the die for forming the honeycomb structure, and formability is deteriorated. Especially, there has been a tendency that the formability drops with decrease of the thickness of a partition wall of the formed honeycomb structure. In the die for forming the honeycomb structure, described in International Publication No. 03/039828, pressure resistance is reduced, but further enhancement of the wear resistance has been expected with the thinning of the partition wall of the honeycomb structure to be manufactured.